| Induction heating power supply has been widely used in the industrial field for its advantages of cleanliness,high efficiency,and high heating speed,such as smelting,diathermy,quenching,bending,welding and other industrial fields.This thesis takes the high frequency induction heating power supply as the research object,the three-phase current-source PWM rectifier(CSR),LLC resonant circuit and inverter phase-locking control methods are theoretically studied and verified by simulation.Firstly,this thesis analyzes and summarizes the development status and development trend of the induction heating power supply,the basic principle of induction heating power supply,the advantages and disadvantages of the DC side power adjust method are proposed.Secondly,in order to solve the problem of low power factor and harmonic pollution on the grid side under the traditional phase rectification control,the three-phase current source PWM rectifier(CSR)is used as a rectifier to reduce harmonic pollution.Gives the topological structure of three-phase CSR and the mathematical model under three-phase stationary and rotating coordinate systems are founded.The modulation method of space vector pulse width modulation(SVPWM)for three-phase CSR is studied,and the parameter design is introduced in detail.Thirdly,this thesis analyzes the topology and circuit characteristics of the LLC resonant circuit.The LLC circuit can replace the high frequency transformer to achieve load matching.The LLC resonant circuit is studied under different load quality factors and different inductance ratios.Gives the parameter design method of LLC resonant circuit.The principle of the phase-locked control of the inverter and analyzes the stability of the phase-locked loop are introduced.The frequency tracking control of phase locked control variable adopts capacitive voltage.When the load parameter changes,it can track the frequency of the loadFinally,the overall structure of the induction heating power supply was designed Introduces the design method of LC Low-pass Filter and DC Energy Storage Inductor.Build a closed loop current mode of three-phase CSR and inverter phase-locked control model based on dq transform model by Matlab/Simulink.The results show that:three-phase CSR can effectively reduce the network side current harmonics,LLC resonant circuit under a single closed-loop control can avoid the inverter damage caused by electricity failure. |
